Rafael Pérez-Pacheco

Inhibition of the growth and development of mosquito larvae of Culex quinquefasciatus (Diptera: Culicidae) treated with extract from leaves of Pseudocalymma alliaceum (Bignonaceae).

OBJECTIVE To determine larvicidal activity of the essential oil, hydrolat and botanical extracts derived from leaves of Pseudocalymma alliaceum on mosquito larvae of Culex quinquefasciatus. METHODS Groups of twenty larvae were used in the larvicidal assays. The mortality, relative growth rate, the larval and pupal duration and viability was estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. RESULTS Essential oil at 800 ppm showed larvicidal activity at 24 h with lethal values of LC50 and LC90 of 267.33 and 493.63 ppm. The hydrolat at 20% and 10% on 2nd stage larvae showed 100% effectiveness after 24 h. The aqueous extract at 10% had a relative growth index of 0.58, while the ethanolic and methanolic extract obtained values of 0.76 and 0.70 and control reached 0.99. Larvae treated with 10% of methanol, ethanol and aqueous extract showed a reduction in larval duration of 5.00, 2.20 and 4.35 days; ethanol extract at 1% provoke decrease of 2.40 days in the development and exhibited an increment of 3.30 days when treated with 0.01%. Aqueous, ethanol and methanol extracts at 10% reduced in 6.15, 3.42 and 5.57 days pupal development. The main compounds were diallyl disulfide (50.05%), diallyl sulfide (11.77%) and trisulfide di-2-propenyl (10.37%). CONCLUSIONS The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat of Pseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration.

Chemical characterization and mosquito larvicidal activity of essential oil from leaves of Persea americana Mill (Lauraceae) against Culex quinquefasciatus (Say)

Abstract Objective To determine chemical composition and mosquito larvicidal activity of essential oil from dried leaves of Persea americana against Culex quinquefasciatus. Methods About 20 larvae in each group were used for larvicidal assays. The mortality, relative growth index, larval and pupal duration and viability were estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. Results The most abundant compounds were estragole (61.86%), sabinene (15.16%) and 1R-α-pinene (14.25%). The essential oil inhibited mosquito larvae growth up to 26.73% [relative growth index (RGI) = 0.74)] and 16.83% (RGI = 0.84) at 800 and 50 mg/L respectively, while the untreated control and group treated with polysorbate 20 showed the RGI of 1.01. The viability of larvae to pupae decreased 53.75% when used 800 mg/L essential oil causing prolongation of development of 14.14 days, while the control had durability in its development of 12 days. In the pupae-adult phase, when used 800 and 50 mg/L of essential oil, 22.36% and 21.81% adults were formed, and there was prolongation of 15.88 days and delay of 13.62 days respectively; however the control showed duration of 14.63 days. Mortality at the end of the experiment was recorded as 57.50% with treatment of 800 mg/L and gradually decreased to 40% with treatment of 50 mg/L essential oil. Conclusions The study demonstrated that the larvicidal activity of essential oil of Mexican avocado inhibited the normal growth and development of mosquito larvae, prolonged larval and pupal duration.

Biological Control of Phyllophaga vetula (Horn)1 with Entomopathogenic Nematodes in Various Formulations and Moisture Conditions

Abstract. The aim of this study was to determine the possibility of using formulations of entomopathogenic nematodes in two soil moisture conditions for effective control of larvae of white grub, Phyllophaga vetula (Horn) (Coleoptera: Melolonthidae). Mortality of P. vetula larvae was compared using Steinernema glaseri Steiner, Heterorhabditis bacteriophora Poinar, and Steinernema feltiae Filipjev in three forms of application (formulated in cadavers of Galleria mellonella L. larvae, bentonite pellet, and aqueous suspension) and two soil moisture conditions (moderate,11.8%, and high, 20.5%). The difference among treatments was very significant: S. glaseri was the most effective nematode, killing 75% of larvae when applied in aqueous suspension with moderate moisture. Next most effective was S. glaseri in cadavers with the same moisture conditions that killed 55%. The nematodes H. bacteriophora and S. feltiae applied in all three forms (aqueous medium, infected cadaver, and bentonite pellet) and with the two moisture conditions (11.8 and 20.5%) were statistically similar to the check and did not control Ph. vetula.

Biological Control of Phyllophaga vetula (Horn)1, and Lethal Concentrations and Times of Entomopathogenic Nematodes

Abstract. Numbers of Phyllophaga vetula (Horn) (Coleoptera: Melolonthidae) larvae killed after application of nematodes Steinernema glaseri Steiner, Heterorhabditis bacteriophora Poinar, and Steinernema feltiae Filipjev at five concentrations (50, 100, 200, 500, and 1,000 nematodes per larva) in aqueous suspension were compared. Lethal concentrations and times for each species were determined. The difference between the treatments was very significant. The nematode most effective for pest control was S. glaseri at a dose of 1,000 per larva that killed 97.5%. H. bacteriophora at the same dose killed 87.5%, and S. feltiae killed 60.0%. With 500 per larva, all three nematodes were statistically the same. S. glaseri at any concentration had the lowest lethal concentration (LC50 and LC95) and lethal time (LT50 and LT95), followed by H. bacteriophora and S. feltiae. The three species of nematodes showed a positive dose-response relationship.

Insecticidal Effect of Botanical Extracts on Developmental Stages of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae)

Abstract. Insecticidal effect of aqueous and ethanol extracts of dried leaves of Ambrosia artemisiifolia L., Piper auritum Kunth, and Taraxacum officinale F. H. Wiggwere determined on developmental stages of potato/tomato psyllid, Bactericera cockerelli (Sulc). When aqueous extract at 0.2 g/ml was applied to psyllid nymphs, A. artemisiifolia extract was most toxic, P. auritum was moderately toxic, and T. officinale was slightly less toxic. Ethanol extract of A. artemisiifolia killed more than 50% of 2nd, 3rd, and 5th instar nymphs treated with 0.001, 0.01, and 0.1 g/ml, respectively. P. auritum was effective on 3rd and 4th instars and T. officinale on 5th and 3rd instars at 0.01 and 0.1 g/ml, respectively. Ethanol extracts of the three plant species killed 50 to 60% of adults with 0.1 g/ml and 30 to 45% with 0.01 g/ml. Extracts of Argemone mexicana L., Azadirachta indica A. Juss, Petiveria alliacea L., and Tagetes filifolia Lag. were evaluated on 4th and 5th instar nymphs. Ethanol extract of leaves of A. mexicana at 0.2 g/ml killed 100% of 5th instar nymphs at 24 hours and 93% of 4th instars at 72 hours. A. indica, P. alliacea, and T. filifolia at 0.2 g/ml killed 85, 88, and 87%, respectively, of 5th instar nymphs.

Effects of aqueous and ethanol extract of dried leaves of Pseudocalymma alliaceum (Bignonaceae) on haematological and biochemical parameters of wistar rats

Abstract Objective To perform the toxicological evaluation of aqueous and ethanol extract of dried leaves of Pseudocalymma alliaceum ( P. alliaceum ) in male Wistar rats by oral administration for 14 days, and to determine the biochemical and haematological status of blood. Methods The animals were completely randomized into four groups of three rats each. Results No deaths were reported after oral administration of the extracts, no physical signs of toxicity or adverse effects were observed. Hematological indices of red blood cell count, hemoglobin concentration and mean corpuscular hemoglobin showed no significant abnormality; however, white series levels decrease presenting a leukopenia. Glucose, creatinine and albumin increased, while urea decreased; aspartate aminotransferase values decreased with the aqueous extract at 50 and 100 mg/kg and increased with dose of 200 mg/kg, in contrast ethanol extract caused an increase in this parameter to the doses used. The alanine aminotransferase decreased with aqueous extract and increased with ethanol extract. Triglycerides decreased when used aqueous extract and reduced with ethanol extract at 100 and 200 mg/kg, in contrast to 50 mg/kg decreased to be compared with control group. Conclusions The daily intake of P. alliaceum did not produce acute toxicity to 50 mg/kg which may be interpreted as toxic signs or biological damage, but liver and renal function changes at dosages of 100 and 200 mg/kg; however, the reduction ability of white blood cells count could be used as a basis for specific studies on the treatment of patients with leukemia.

Repellency, toxicity, and oviposition inhibition of vegetable extracts against greenhouse whitefly Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae)

In a search for sustainable options of greenhouse whitefly Trialeurodes vaporariorum (Westwood) management, the toxic and/or repellent potential of water, ethanolic, and acetonic extracts of Ambrosia artemisiifolia L. (Asteraceae), Comocladia engleriana Loes (Anacardiaceae), Piper auritum Kunth (Piperaceae), Raphanus raphanistrum L. (Brassicaceae), and Taraxacum officinale F.H. Wigg. aggr.* (Asteraceae) were evaluated. Repellency was assessed by the cylinder method (olfactometer), while toxicity and oviposition inhibition were assessed by the leaf immersion method. Acetonic extracts did not cause any repellent or insecticidal effect. In contrast, 200 mg mL-1 water and ethanolic extracts of R. raphanistrum and ethanolic extract of A. artemisiifolia had the highest repellent activity (76%, 72%, and 69%, respectively) although their activity decreased gradually over time. Ethanolic extracts of P. auritum (66%) and R. raphanistrum (56%) at 200 mg mL1 were highlighted as being toxic, while the most effective in inhibiting oviposition were water extracts of R. raphanistrum (76.1%) and P. auritum (72.0%) and ethanolic extract of P. auritum (69.5%); however, concentrations lower than 60 mg mL-1 caused oviposition stimulation. Our results suggest that water and ethanolic extracts of R. raphanistrum and P. auritum represent a useful tool in integrated whitefly management.

Effects of Salinity and pH on the Infective Capacity of Romanomermis iyengari and Romanomermis culicivorax in Larvae of Culex quinquefasciatus Mosquito

Abstract. Effects of salinity and pH were assessed on the infective capacity of parasitic nematodes of mosquitoes Romanomermis culicivorax Ross & Smith and Romanomermis iyengari (Welch), on larvae of southern house mosquito, Culex quinquefasciatus Say. Thirteen pH levels (3.6, 3.8, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.2, and 8.4) were evaluated. Six salinity levels (NaCl concentrations) were evaluated, with values of 0.01 M (584 mg/L), 0.02 M (1,169 mg/L), 0.03 M (1,753) mg/L), 0.04 M (2,338 mg/L), 0.05 M (2,922 mg/L), and a 0.00 M check, with three replications. Percentage of infection (of parasitized larvae) and infestation intensity (average nematodes parasitizing a mosquito larva) were recorded for both factors. To determine effects of pH and salinity on percentage of infection and infestation intensity, a sample (n = 20, IV instar) of larvae surviving at high salinity levels was extracted 5 days after application. The greatest percentage of infection statistically significant in R. iyengari was 75 to 91.7 for pH 5.0 to 7.5, and 86.7 to 100 for R. culicivorax between pH 6.0 and 7.0. The greatest infestation intensity statistically significant in R. iyengari was 4.42 to 8.45 between pH 4.5 and 8.0. The greatest levels of infestation statistically significant in R. culicivorax were between pH 5.0 and 7.5 with 3.07 and 3.63 nematodes per mosquito larva.

Larvicidal effect of Clinopodium macrostemum essential oil extracted by microwave-assisted hydrodistillation against Culex quinquefasciatus (Diptera: Culicidae)

INTRODUCTION In the present study, we determined the chemical composition of Clinopodium macrostemum essential oil obtained by microwave-assisted hydrodistillation and its effect on the growth and development of Culex quinquefasciatus mosquito larvae. METHODS The essential oil compounds were identified by gas chromatography-mass spectrometry analysis, and bioassays were conducted to evaluate the influence on the developmental stages of early second instar larvae of Cx. quinquefasciatus until the emergence of adults, using essential oil concentrations of 50, 100, 200, 400, and 800mg/L. RESULTS The gas chromatography-mass spectrometry analyses revealed that the leaf essential oil of C. macrostemum contained 32 compounds and the major chemical compounds identified were linalool (55.4%), nerol (6.4%), caryophyllene (6.25%), menthone (5.8%), geraniol acetate (4.1%), terpineol (3.7%), and pulegone (2.8%). The essential oil yield obtained by microwave-assisted hydrodistillation was 0.8% at 20 min. The treatments showed lethal concentrations (LC50 and LC90) of 22.49 and 833.35mg/L, respectively, after the final measurement of the total number of dead larvae (second, third, and fourth instars), and LC50 and LC90 of 6.62 and 693.35mg/L, respectively, at the end of the experimental period. The essential oil inhibited the growth and development of the mosquito larvae by 32% (relative growth index = 0.68) at 50mg/L, and up to 47% (relative growth index = 0.53) at 800mg/L. CONCLUSION The present study demonstrated the larvicidal effect of C. macrostemum essential oil on Cx. quinquefasciatus, which can be attributed to the oxygenate compounds obtained by the extraction method.

First Report of the Platynota n. sp. (Lepidoptera: Tortricidae) Genus in Prickly Pear (Opuntia spp.) in the Municipality of Villa Milpa Alta, Mexico DF, Mexico

Abstract A new genus of Platynota n. sp. was registered for the first time in Opuntia spp. crops in the municipality of Villa Milpa Alta, Mexico DF. The morphological characteristics of the immature and adult stages are described, as well as their damage to the fruit.